JP2002075905A - Method of manufacturing semiconductor device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a new method of manufacturing semiconductor device that is ideal for the formation of a low-resistance silicide layer. SOLUTION: In the method of manufacturing semiconductor device, metal silicide layers 11 are formed in self-aligning ways on source and drain regions 3 and 4 and a gate electrode 5 formed in and on the surface of a semiconductor substrate 1 exposed through an insulating film 2 selectively formed on the substrate 1. The metal silicide layers 11 are formed by causing cobalt 6 to deposit on the substrate 1 and heat-treating the cobalt 6. At the time of etching off unreacted cobalt thereafter, the etching is performed by using an etchant prepared by mixing hydrochloric acid, hydrogen peroxide, and water with each other at a concentration ratio of 1:1:5 to 3:1:5 under a condition where the temperature of the etchant and the etching time are adjusted to 25-45 deg.C and 1-20 minutes, respectively.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for manufacturing a semiconductor device, and more particularly to a method for manufacturing a semiconductor device suitable for forming a low-resistance silicide layer.

[0002]

2. Description of the Related Art Shallow junction high-speed logic device and DR
In order to realize an AM / logic hybrid device, it is necessary to reduce the resistance of the gate, source, and drain electrodes by a salicide process, and the cobalt salicide technology is used from the viewpoint of the fine wire effect and heat resistance. When impurities for suppressing the silicide reaction are implanted into a silicon substrate on which a diffusion layer electrode or a gate electrode, or both a diffusion layer electrode and a gate electrode of a semiconductor element are formed, a locally low-resistance and uniform cobalt silicide film is formed. Some areas are not formed.

[0003]

In order to improve the situation in which cobalt silicide is hardly formed locally (defective formation), it was investigated which step of the cobalt salicide process greatly affects the formation failure. As a result, the first
In the process of removing the unreacted cobalt and the partially oxidized cobalt film after sintering, it was found that the formation of a silicide layer was poorly performed by increasing the temperature of the etchant or performing the etching for a long time. .

An object of the present invention is to improve the above-mentioned drawbacks of the prior art and to provide a novel method of manufacturing a semiconductor device which is particularly suitable for forming a low-resistance silicide layer.

[0005]

SUMMARY OF THE INVENTION The present invention basically employs the following technical configuration to achieve the above object.

That is, a first aspect of the method of manufacturing a semiconductor device according to the present invention is that a source / drain region formed in a portion exposed from an insulating film selectively formed on a semiconductor substrate and a gate electrode are formed on a gate electrode. In a method of manufacturing a semiconductor device in which a metal silicide layer is formed in a self-aligned manner, cobalt is deposited on the semiconductor substrate, and heat treatment is performed to form the metal silicide layer, and thereafter, unreacted cobalt is etched. When removing by etching, the respective concentration ratios of the etching solution composed of a mixed aqueous solution of hydrochloric acid, hydrogen peroxide and water are set to 1: 1: 5 to 3: 1: 5, the liquid temperature is set to 25 to 45 ° C., and the etching time is set to The etching is performed under the conditions of 1 to 20 minutes.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A method of manufacturing a semiconductor device according to the present invention is directed to a method of manufacturing a semiconductor device in which a source / drain region formed in a portion exposed from an insulating film selectively formed on a semiconductor substrate and a gate electrode are self-aligned. In a method of manufacturing a semiconductor device, wherein a metal silicide layer is formed on a semiconductor substrate, cobalt is deposited on the semiconductor substrate and heat treatment is performed to form the metal silicide layer, and thereafter, unreacted cobalt is removed by etching. In this case, the respective concentration ratios of the etching solutions composed of a mixed aqueous solution of hydrochloric acid, hydrogen peroxide and water are set to 1:
Etching is performed under conditions of 1: 5 to 3: 1: 5, liquid temperature of 25 to 45 ° C., and etching time of 1 to 20 minutes.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A specific example of a method for manufacturing a semiconductor device according to the present invention will be described below in detail with reference to the drawings.

(First Specific Example) FIGS. 1 and 2 are process diagrams for explaining a first specific example.

In the present invention, first, as shown in FIG. 1A, the entire surface of a semiconductor substrate 1 on which elements are formed is
As shown in (b), a film of cobalt 6 is formed. The film forming temperature at this time is 200 to 500 ° C., and the film is formed by magnetron sputtering. Next, this is heat-treated for 30 seconds in an inert gas atmosphere of 500 ° C. or more, for example, in a nitrogen atmosphere, to obtain a dicobalt silicide film (Co ₂ Si),
A cobalt monosilicide film (CoSi) and a cobalt disilicide film (CoSi ₂ ) are formed (first sinter). At this time, the cobalt silicide layer is formed in a self-aligned manner only on the gate electrode 5 and the diffusion layers 3 and 4, as shown in FIG. Then, the silicon substrate 1 is immersed in a mixed aqueous solution (HPM) of hydrochloric acid, hydrogen peroxide, and water to selectively wet-etch and unreact or partially oxidize the field oxide film 2 and the sidewall film. Only the removed cobalt film is removed by etching (FIG. 1D). In this surplus cobalt etching process, it is necessary to optimize the etching conditions in order to avoid the etching of the surface of the gate electrode 5 and the silicide films of the source / drain regions 3 and 4 due to excessive etching. Water concentration ratio of 1: 1: 5 to 3:
1: 5, the temperature of the HPM solution is 25 to 45 ° C., and the etching time is 1 to 20 minutes. Next, a heat treatment is performed for 10 seconds at a temperature higher than that of the first sintering, for example, 800 ° C. (FIG. 1).
(E)). As a result, low resistance and uniform cobalt disilicide (CoSi ₂ ) is formed (second sinter).

Next, the surplus cobalt etching process will be further described with reference to FIG.

After the first sintering, any one of a dicobalt silicide film, a cobalt monosilicide film, a cobalt disilicide film, or a mixed film thereof is formed depending on the temperature. In that state, in order to remove unreacted cobalt or oxides of cobalt on the field oxide film and the sidewalls, selective wet etching, that is, excess cobalt etching is performed.
When excessive etching is performed, specifically, the etching liquid enters through the crystal grain boundaries of the cobalt silicide crystal due to long-time etching, and the etching liquid is not affected by the influence of the base, for example, the impurity implantation. By etching a stable cobalt silicide film, impurities present at the interface between the cobalt silicide film and the silicon substrate, impurities in the substrate, and the like, a state where the silicide film is locally etched is obtained (FIG. 2B). In this state, even if the second sintering is performed thereafter, a low-resistance and uniform cobalt silicide film cannot be formed.

In order to eliminate such a problem, in the step of removing unreacted cobalt or cobalt oxide, only the unreacted cobalt and the partially oxidized cobalt film are removed by etching without affecting the silicide film. Therefore, it is necessary to lower the etching rate or to prevent the etching liquid from being immersed in the etching solution for an excessive time. According to the experiments of the present inventors, the etching solution was a mixed aqueous solution of hydrochloric acid, hydrogen peroxide solution and water, and the concentration ratio was 1: 1: 5 to 5: 1.
It was optimal to perform the etching at a ratio of 3: 1: 5, a liquid temperature of 25 to 45 ° C., and an etching time of 1 to 20 minutes. For example, when the temperature of the etching solution is 35 ° C. and the etching time is 3 minutes, only the unreacted cobalt and the oxide of cobalt are etched, and the silicide layer is not etched at all (FIG. 2C). Thereafter, the second sintering was performed to form a low-resistance and uniform cobalt silicide film (CoSi ₂ ) 11. The occurrence of defects is
It greatly depended on the concentration of the etching solution, the solution temperature, and the etching time.

When the concentration, the liquid temperature and the etching time of the etching solution are set below the above ranges, unreacted cobalt and oxides of cobalt cannot be completely removed. If it is set to a value higher than the above range, the silicide layer will be etched. Therefore, it was concluded that the above range was the optimum etching condition.

(Second Embodiment) FIGS. 3 and 4 are process diagrams for explaining a second embodiment of the present invention.

First, as shown in FIG. 3A, a cobalt 6 film is formed on the entire surface of the semiconductor substrate 1 on which the elements are formed, as shown in FIG. 3B. Here, after forming the cobalt 6, a film of titanium (Ti) or titanium nitride (TiN) 7 is formed to prevent oxidation of the cobalt 6, and covers the cobalt 6 (FIG. 3C). As a film forming method, a film is formed by a magnetron sputtering method or vapor deposition. In this state, 500 ° C
Heat treatment for 10 to 60 seconds in the above inert gas atmosphere,
A dicobalt silicide film, a cobalt monosilicide film, and a cobalt disilicide film are formed (first sinter). At this time, the cobalt silicide layer 10 is formed only on the gate electrode 5 and the diffusion layers 3 and 4 in a self-aligned manner (FIG. 4A). Next, in order to remove the titanium or titanium nitride film 7 formed as a cap film for preventing oxidation during the formation of the cobalt 6, the silicon substrate 1 is placed in a mixed aqueous solution (APM) of ammonia, hydrogen peroxide and water. Immersion (FIG. 4B). Thereafter, the silicon substrate 1 was immersed in a mixed aqueous solution (HPM) of hydrochloric acid, hydrogen peroxide, and water to selectively wet-etch and unreacted or partially oxidized the field oxide film and the sidewall film. Only the cobalt film is removed (FIG. 4C). At this time, it is necessary to optimize the etching conditions to avoid etching of the surface of the gate electrode 5 and the silicide films of the source / drain regions 3 and 4 due to excessive etching. The conditions include hydrochloric acid, hydrogen peroxide, and water. To 1: 1: 5 to 3: 1: 5, and the temperature of the HPM solution to 25 to 4
Etching was performed at 5 ° C. for 1 to 20 minutes. Then, at a temperature equal to or higher than the time of the first sinter, 10 to 6
Heat treatment is performed for 0 seconds (FIG. 4D). As a result, a low resistance and uniform cobalt disilicide 11 was formed.

[0017]

According to the method of manufacturing a semiconductor device of the present invention, in the step of removing the unreacted or partially oxidized cobalt film, the concentration ratio of the etching solution consisting of a mixed aqueous solution of hydrochloric acid, hydrogen peroxide and water is adjusted. 1: 1: 5 to 3: 1: 5, the liquid temperature is 25 to 45 ° C., and the etching time is 1 to 5.
Even if the dicobalt silicide film, the cobalt monosilicide film, and the cobalt disilicide film are unbalanced on the gate electrode or the diffusion layer electrode by etching for 20 minutes, the silicided cobalt film is not etched, Only unreacted cobalt or partially oxidized cobalt could be removed by etching. Therefore, by performing a high-temperature heat treatment in the next step, a uniform and low-resistance cobalt disilicide film can be formed, and as a result, an excellent effect of improving product yield and long-term reliability can be obtained.

[Brief description of the drawings]

FIG. 1 is a sectional view showing steps of a first specific example of a method for manufacturing a semiconductor device according to the present invention.

FIG. 2 is a diagram illustrating a difference between the present invention and a conventional example.

FIG. 3 is a cross-sectional view showing a process of a second specific example of the method for manufacturing a semiconductor device according to the present invention.

FIG. 4 is a view showing a step that follows the step shown in FIG. 3;

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 silicon substrate 2 LOCOS oxide film 3 drain region 4 source region 5 gate electrode 6 cobalt (Co) film 7 titanium (Ti) or titanium nitride (TiN) film 10 CO₂Si, COSi, COSi₂  11 COSi₂film

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) H01L 21/336 H01L 29/78 301P // C23F 1/28 F term (Reference) 4K057 WA01 WA10 WB01 WB03 WE08 WE25 WG02

Claims (1)

[Claims] 1. A method of manufacturing a semiconductor device in which a metal silicide layer is formed in a self-aligned manner on a source / drain region and a gate electrode formed in a portion exposed from an insulating film selectively formed on a semiconductor substrate. Forming a metal silicide layer by depositing cobalt on the semiconductor substrate and performing heat treatment, and then removing unreacted cobalt by etching, a mixed aqueous solution of hydrochloric acid, hydrogen peroxide, and water; The concentration ratio of each of the etching solutions consisting of 1: 1: 5 to 3: 1: 5, and the solution temperature being 2: 1
A method for manufacturing a semiconductor device, characterized in that etching is performed under conditions of 5 to 45 ° C. and an etching time of 1 to 20 minutes.